Featured Research

from universities, journals, and other organizations

Ultra-short laser pulses control chemical processes

Date:
December 12, 2012
Source:
Vienna University of Technology
Summary:
Specially shaped laser pulses can be used to change the state of electrons in a molecule. This process only takes several attoseconds -- but it can initiate another, much slower process: The splitting of the molecule into two parts. Laser pulses can be used to initiate or suppress chemical reactions in a controlled way.

A short laser pulse hits a molecule (here: Butadiene), which splits into two parts.
Credit: Image courtesy of Vienna University of Technology

Chemical reactions occur so quickly that it is completely impossible to observe their progress or to control them using conventional methods. However, new developments in electrical engineering and quantum technology enable us to achieve a more exact understanding and improved control of the behaviour of atoms and molecules. At the TU Vienna, scientists have succeeded in influencing the splitting of large molecules with up to ten atoms using ultra-short laser pulses.

The flash of light which splits molecules Splitting a molecule is an example of an elemental chemical reaction. The splitting of molecular bonds with a laser pulse is relatively simple. It is much more difficult, however, to influence the splitting of a specific bond in a controlled manner, i.e. to initiate it in a controlled manner or to suppress it. In order to achieve this, the complex processes must be altered at an atomic level. This is carried out at the Institute for Photonics at the TU Vienna using specially-shaped laser pulses, with a duration of only a few femtoseconds. One femtosecond (10-15 seconds) is one millionth of a billionth of a second.

Fast electrons, slow atomic nuclei

One carbon atom has a mass around 22,000 times greater than an electron. It is therefore also relatively inert and cannot be moved easily from its position. A laser pulse can therefore change the movement of the small, light electrons much more rapidly than that of the atomic nuclei: One electron can be extracted from the molecule, then reversed using the laser pulse field and collided again with the molecule. During this collision, the electron can subsequently extract a second electron from the molecule. A doubly charged molecule remains, which can then split into two singly charged fragments under certain circumstances.

"Usually, it takes several femtoseconds for the atomic nuclei to reach a sufficient distance from one another and the molecule to split into two pieces," explains Markus Kitzler from the Institute of Photonics at the TU Vienna. The collision of the electron with the molecule only lasts several hundred attoseconds (10-18 seconds). "We therefore have to deal with two separate timescales," explains Kitzler. "Our specially shaped ultra-short laser pulses affect rapidly-moving electrons. The fact that the state of the electrons is changed by the collision also sets the large, slow atomic nuclei into motion." Using this technique, the TU research team have for the first time been able to show that specific elemental chemical reactions using various hydrocarbon molecules can also be initiated or suppressed in a controlled manner, if the movement of the atomic nuclei are influenced indirectly by the much quicker electrons. The exact shape of the laser pulse is crucial in this process.

The role of electron movement for chemistry

In order to be able to interpret the experimental data correctly and understand what actually happens during these incredibly rapid processes at atomic and electronic level, theoretical calculations and computer simulations are required. This has also been carried out at the TU Vienna -- at the Institute for Theoretical Physics, which collaborates with the Institute for Photonics on attosecond projects. Using this method, we can do more than simply observe whether and how a molecule splits. "The experiments and simulations show how the sequence of chemical processes can also be affected in a targeted manner using precise control of the laser pulse," explains Katharina Doblhoff-Dier from the Institute of Theoretical Physics.


Story Source:

The above story is based on materials provided by Vienna University of Technology. Note: Materials may be edited for content and length.


Journal Reference:

  1. Xinhua Xie, Katharina Doblhoff-Dier, Stefan Roither, Markus Schφffler, Daniil Kartashov, Huailiang Xu, Tim Rathje, Gerhard Paulus, Andrius Baltuška, Stefanie Grδfe, Markus Kitzler. Attosecond-Recollision-Controlled Selective Fragmentation of Polyatomic Molecules. Physical Review Letters, 2012; 109 (24) DOI: 10.1103/PhysRevLett.109.243001

Cite This Page:

Vienna University of Technology. "Ultra-short laser pulses control chemical processes." ScienceDaily. ScienceDaily, 12 December 2012. <www.sciencedaily.com/releases/2012/12/121212130848.htm>.
Vienna University of Technology. (2012, December 12). Ultra-short laser pulses control chemical processes. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2012/12/121212130848.htm
Vienna University of Technology. "Ultra-short laser pulses control chemical processes." ScienceDaily. www.sciencedaily.com/releases/2012/12/121212130848.htm (accessed July 22, 2014).

Share This




More Matter & Energy News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Government Approves East Coast Oil Exploration

Government Approves East Coast Oil Exploration

AP (July 18, 2014) — The Obama administration approved the use of sonic cannons to discover deposits under the ocean floor by shooting sound waves 100 times louder than a jet engine through waters shared by endangered whales and turtles. (July 18) Video provided by AP
Powered by NewsLook.com
Sunken German U-Boat Clearly Visible For First Time

Sunken German U-Boat Clearly Visible For First Time

Newsy (July 18, 2014) — The wreckage of the German submarine U-166 has become clearly visible for the first time since it was discovered in 2001. Video provided by Newsy
Powered by NewsLook.com
Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Reuters - US Online Video (July 17, 2014) — President Barak Obama stopped by at a lunch counter in Delaware before making remarks about boosting the nation's infrastructure. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

TheStreet (July 16, 2014) — Oil Futures are bouncing back after tumbling below $100 a barrel for the first time since May yesterday. Jeff Grossman is the president of BRG Brokerage and trades at the NYMEX. Grossman tells TheStreet the Middle East is always a concern for oil traders. Oil prices were pushed down in recent weeks on Libya increasing its production. Supply disruptions in Iraq fading also contributed to prices falling. News from China's economic front showing a growth for the second quarter also calmed fears on its slowdown. Jeff Grossman talks to TheStreet's Susannah Lee on this and more on the Energy Department's Energy Information Administration (EIA) report. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins